Prior through the wall stovepipe installations were primarily adaptable for use with solid fuel, such as wood or coal and thus were required to be associated with an upstanding chimney, thus necessitating insulation only along the junction between the stove and the chimney. As an example of such prior assembly see U.S. Pat. No. 4,543,942, dated Oct. 1, 1985 and the references cited therein.
These prior devices not only required insulation against one structural wall but insulation along the stove pipe itself as it came within the proximity of such wall, with the insulation penetrating into the upright chimney. Thus these assemblies were expensive to manufacture and difficult to install.